Microsoft’s Windows Phone efforts are finally over, judging by a series of tweets from Windows 10 chief Joe Belfiore.

A few months back, Microsoftmsftended support for its Windows Phone 8.1 platform. However, that version was succeeded by Windows 10 Mobile—a more handset-friendly version of Microsoft’s desktop operating system.

Responding to questions from Windows Phone users on Sunday, Belfiore said Microsoft would still provide bug fixes and security updates for Windows 10 Mobile, but building new features and hardware is no longer a focus for the company.

It’s no surprise that Microsoft has turned its back on the smartphone operating system market. The firm laid off thousands of workers last year as it slashed the mobile business it had bought from Nokia in 2014—a purchase that led to a $ 7.6 billion write-off.

Last month, Microsoft co-founder Bill Gates outed himself as an Android user. On Sunday, Belfiore said that he too had “switched platforms for the app [and hardware] diversity.”

The lack of app diversity on Microsoft’s mobile platforms was a big problem for the company. Developers of mobile apps, dealing with limited resources, go for the most popular platforms first in order to recoup their investments; without a hefty app roster, it’s near-impossible for an underdog platform to take on its larger rivals.

“We have tried VERY HARD to [incentivize] app devs,” Belfiore wrote. “Paid Monday… wrote apps 4 them… but volume of users is too low for most companies to invest.”